The present invention relates to an image recorder of the type printing out an image on a recording medium in the form of a sheet and then driving it thereoutof. More particularly, the present invention is concerned with a finisher for stapling a set of sheets sequentially driven out from such an image recorder and stacking the resultant stapled sets on a tray.
A finisher of the type described is extensively used with image recorders such as copiers and printers. The finisher binds a plurality of sets of sheets one by one while sequentially stacking them on a tray. It is a common practice with such a finisher to staple, i.e., to drive staples into all the sets of sheets at the same position. This brings about a problem that as the stapled sets are sequentially stacked on a tray, only the portions thereof adjacent to the staples rise relative to the other portions. As a result, the number of stapled sets which can be stacked on the tray and, therefore, the efficiency is reduced. Moreover, it is likely that the staple driven into a set of sheets being driven out onto the tray catches the staple of a stapled set which has already been stacked on the tray, resulting in the incomplete discharge and disorderly stacking of stapled sets.